


Blue Eyed Monster

by TerrifiedAristocrat



Category: Ao no Exorcist | Blue Exorcist
Genre: Alternate Timelines, Alternate Universe, Canon-Typical Violence, Crossover, Other
Language: English
Status: In-Progress
Published: 2015-01-01
Updated: 2015-01-01
Packaged: 2018-03-04 18:31:59
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,806
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/3081341
Author URL: https://archiveofourown.org/users/TerrifiedAristocrat/pseuds/TerrifiedAristocrat
Summary: <blockquote class="userstuff">
              <p>An AU where Yukio becomes a demon at a young age, kills his brother and goes about causing trouble while Shirou lives and tracks him down. Sometimes this trouble involves invading a parallel universe. Sometimes Shirou follows.</p>
            </blockquote>





	Blue Eyed Monster

Bad things happened when Mephisto’s eyes itched.

It was different which each vessel, he’d found, but in this one it was the eyes. They sat in his scull and itched and watered, making playing the most recent handheld RPG game rather difficult.

Something was amiss- not in the way that mice scurrying through a pantry was amiss but in the same way an intruder in a house was amiss, a stranger from a different country with smoke on his feet and murder on his breath.

And as Mephisto went in search of a handkerchief and a means to investigate the cause of his discomfort, a stranger padded carefully down the halls of True Cross Academy. He found a student, poor soul, pulled him into the shadows and snapped his neck. It was pitifully easy, and he wasted no time in swapping out the corpse’s clothes and leaving the body where it wouldn’t be found for a day or two. 

He slunk out in the halls, changing his gait to one that matched the other filthy humans milling about. Someone was shouting, this stranger noted with a twinge of irritation. He had a feeling that the someone was calling for him.

"YU-KI-O!" the someone bellowed and the stranger stopped- that was his name. He turned and saw two humans approaching him, one of whom looked to be about his height with messy black hair, an unevenly kept uniform and some strap on his shoulder. The other was a young woman of shorter stature with fair skin and blonde hair and pretty green eyes he’d love to pluck out. 

"Oi," the male approached Yukio and touched- no, slapped- his shoulder. Yukio tensed, the desire to bare his fangs rising. "Are you deaf?"

"No," Yukio replied levelly. "I was thinking,"

"You think too much," the male informed Yukio.

"I don’t think so," the female remarked shyly, in the kind of voice that would sound beautiful in a scream. Yukio smiled kindly at her and her face split into a glowing smile. If Yukio worked a little he could surely charm that kimono right off of her…

"Anyway." the male coughed pointedly and shoved a container into Yukio’s hands. "You forgot your lunch." A bell rang and the male sort of jumped. "I gotta go catchya later!" he ran off, his female friend pausing before pattering after him. She glanced back- Yukio smiled charmingly at her again and for a moment she hesitated.

"C’mon Shiemi, you’ve got your classes too, right?" the boy urged her.

"Mmm coming," Shiemi hurried after, and Yukio turned to keep moving. If he stayed still in one place, he would get found.

Besides, the place reeked of his brother Samael. That creature was awfully troublesome and Yukio was rather lucky he’d learned things from his fatehr, or he’d be dead. Yukio continued moving, hoping that cursed paladin didn’t follow him across the boarder…

______________________________________________________

"PHELES."

It had been a while since Shura raised her voice at the demon- if it wasn’t for the fact that his eyes throbbed Mephisto would have relished it. Shura burst into his office, pale with wide eys and her mouth pressed into a firm, and irritated line.

"Ah Miss Kirigakure what brings you-"

"Shirou’s here." she cut him off, her voice hollow. That got Mephisto’s attention. 

"He’s-"

"Dead. I know." Shura cut him off. "Funny thing is, the phrase ‘you should be dead’ was the first thing out of his mouth when he saw me," Mephisto stood, his eyes narrowed.

"How did he seem, off?" he asked. Shura shook her head.

"Yes and no. He smokes. He doesn’t smile, but I only talked to him for less than five minutes. He’s heavily armed. He looked sad when he saw me at first," she reported. That was not the information Mephisto was looking for- if someone was foolhardy enough to attempt to raise Shirou from the dead through the various outlets he was aware of, Shirou would be off, but not like that. The demon tapped his chin, thinking.

"Where is he?" he asked. Shura indicated with a jerk of her head to follow him, pausing for a moment.

"Should we tell the twins?" she asked carefully Mephisto raised his eyebrows- while it would be deliciously amusing to see their reactions, Rin would make a mess. Yukio might make one too, but not as big of one.

"There is no need to pull them from classes," he dismissed her. Shura nodded and continued leading Mephisto.

He was fairly close- the priest who should be dead was in a hallway, standing over a dead student. As they approached, Shirou looked up. Shura was right- the man was heavily armed and smoking.

"Pheles," he sounded tense, but certainly like Shirou. "You have a problem," He nudged the corpse with his toe, frowning.

"So it would seem," Mephisto agreed. Shura positioned herself at Mephisto’s side, but closer to Shirou than Mephisto. 

"She’s supposed to be dead," Shirou remarked, jerking his head in Shura’s direction. "I buried her myself," 

"Technically speaking, you’re supposed to be dead. While I didn’t bury you myself …" Mephisto trailed off, not feeling the strong urge to admit that he watched the circumstances of Shirou’s death in front of Shura. Besides- Yukio was rounding the corner, perhaps a hall or so to the west. There was a possibility that he’d come across this scene. 

"Huh." Shirou paused for a moment, scratching his chin. "Oh. Right, you said something to me about parallel universes. Wrote a letter an everything,"

"Ah yes. I would have made such precautions," Mephisto nodded in agreement. Parallel worlds were… well, they were very troublesome, but explained Shirou’s existence. The paladin handed over a letter written in Mephisto’s own favorite stationary, which the demon skimmed over without particularly reading. "I must ask how you got here though- trans-dimensional travel in itself is difficult enough, moving from one parallel world to another is even more so,"

(At this point Shura was making that face she made whenever Mephisto decided to talk about metaphysics around her, which made Shirou smile)

"I don’t know how he did it," Shirou shook his head. "I simply followed him. I must capture him, before he kills again," Shirou nudged the corpse again. Yukio turned the corner, rushed and late for class. He stopped in the middle of the hall, facing Shirou’s back with a look of absolute confusion. 

"What kind of a creature are we talking about?" Shura asked seriously.

"He’s the son of Satan. He kept the name I gave him, Yukio, out of spite I’d imagine," Shirou told Shura. 

Oh.

"What?" Shura spoke first- she was the next one to see Yukio Okumura standing in a hall, his face pale, his eyes wide, his mouth trembling. Shirou turned and without hesitation raised his gun to the young exorcist, firing a round. 

Yukio ducked and Shura flung herself at Shirou, grabbing his gun hand.

"What the hell are you doing-"

"What the hell are you doing he’s right there I’m not going to watch him kill you again!” Shriou spat back, wrestling with the red-head. 

"Yukio is your son why would he kill me?" Shura snapped.

"That is no son of mine," Shirou told Shura coldly, turning to stare at the exorcist picking himself off the ground. Yukio stared at Shirou, wide eyed still although his lip wasn’t trembling as much. He was silent, hiding.

"Ahem." Mephisto cleared his throat. "Before we get too excited, I should remind you that you are from a parallel world. Things work a little differently here. The young man over here is Yukio Okumura, an exorcist you yourself taught."

Shirou squinted at Yukio, analyzing. Finally, he lowered his gun.

"Perhaps we should discuss this in more detail in my office," Mephisto suggested. Shirou nodded, as did Shura. "I will inform your instructor of your absence, "Mephsto added, glancing at Yukio. the boy nodded, watching Shirou silently.

The procession to Mephisto’s office was a solemn, silent one. Shura was torn- on one hand she missed Shriou. She missed his smile and his laugh, his filthy jokes and even his stern lectures.

But holy shit Shirou was a jackass.

Shura didn’t like how quiet Yukio was being- she had to glance back a few times to make sure the boy was following. He was, staring blankly at the back of Shirou’s head. He was thinking too much or in too much pain or maybe even both- and knowing the moron he wasn’t going to say anything to anyone about it. Ugh. Shura was going to have to have a talk to him.

Mephisto opened a door and let everyone into his office. Soon the three of them were sitting in chairs around Mephisto’s desk, Shura sitting in between Yukio and Shirou. The paladin peered over at Yukio again, frowning.

"Your ears aren’t pointed, "He remarked slowly. "They look human," 

"That’s because I am human," Yukio replied softly. Shirou looked into his lap for a few moments. 

"That was rude of me, I should have looked before I shot," he stated. "Please accept my apology,"

Yukio nodded shakily.

"This raises a bigger problem," Shura spoke up carefully. She turned to Shirou. "There’s someone who looks like Yukio running around this school."

"Someone dangerous," Shirou agreed. 

"We must find him," Yukio spoke up firmly. "Before he finds someone who knows me and hurts them,"

"He would. Do you have very many friends?" Shriou asked. Yukio frowned, thinking.

"N…No, not really," he shook his head. " But I teach-" Yukio paused, Shiemi’s face coming to mind. "I teach Anti-demon Pharmacology though and have students…"

"You’re teaching?" Shirou squinted. He then added "I usually teach that class,"

"In this world you’re dead," Shura reminded Shirou quietly.

"I’m a middle-class exorcist with a meister in dragoon and doctor," Yukio explained simply, without pride or arrogance. "Your death was… sudden. I happened to be in the area and took your place," Those were the facts. Yukio had hoped, in the back of his head, that Shirou would look proud of him.

Instead the man looked concerned, and shot Mephisto a glance. Mephisto smiled and sipped some tea.

"Well then. It seems you all are going monster-hunting!" he chirped.

"Maybe you should stay here," Yukio remarked to Shirou.

"Why?" Shirou asked.

"Rin," Yukio replied. Shirou’s eyes widened.

"Rin’s alive?" he asked. 

"Yeah," Shura stepped in on the conversation. "If he finds yer that may be a problem,"

"We don’t have the luxury to be down one exorcist," Mephisto shook his head. "I want this demonic Yukio in my office as soon as possible, dead or alive,"

"Right. C’mon," Shura headed for the door, grabbing Yukio’s arm. Shirou followed, shooting Mephisto one last questioning glance before leaving.

The demon smiled.

Maybe this would be entertaining after all.


End file.
